Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

450
FXUS63 KLOT 240810
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
310 AM CDT Wed Jun 24 2026

.KEY MESSAGES...

- Chance of thunderstorms today, some possibly becoming severe
  in the afternoon.

- Turning hotter and more humid into early next week.

&&

.DISCUSSION...
Issued at 310 AM CDT Wed Jun 24 2026

A mid/upper-level trough, and an attendant surface low, moving
into the Upper Midwest this morning, will move across the
western Great Lakes later today into tonight. As it does, our
primary forecast concerns will center around thunderstorm
coverage, timing and severity today. Initially, we will be
monitoring an area of ongoing showers and non-severe
thunderstorms to our north- northwest across far southern
MN/northern IA eastward into southern WI. This activity is
expected to gradually sag southward across far southern WI
towards the IL state line by around daybreak this morning. We
are not expecting any severe threat with this morning activity,
but there is likely to be some scattered showers and a few
thunderstorms this morning, particularly across far northern IL
(I-88 and north). Thereafter, attention turns towards the
likelihood for additional thunderstorm development this
afternoon into this evening.

This afternoon, a moistening low-level airmass (dewpoints
climbing into the low to mid 60s) is expected to diurnally
destabilize in the wake of this mornings activity, and in
advance of an approaching cold front. As this occurs, there
continues to be a general consensus that this will support
scattered thunderstorm development across southern WI southward
into northern IL after 2 to 3 PM. The environment in which these
storms develop will be amply sheared, owing to the presence of
an enhanced belt of westerly mid-level flow (45-50 kt) moving
out across the warm sector. Accordingly, storm organization and
an associated severe threat will exist with the strongest
clusters later today into early this evening. It appears the
primary severe threats will be damaging wind gusts in excess of
60 mph. However, a few instances of severe hail will also be
possible, particularly in association with any supercells. Storm
motions will ultimately favor scattered storm clusters and
supercells to shift east-southeastward across northeastern IL
into northwestern IN into this evening before weakening later in
the evening with the passage of the cold front.

On Thursday, the surface cold front is expected to stall out
and become west-to-east oriented across downstate IL and IN as
the next surface low sets up across the southern Plains. This
front will continue to be the main focus for additional shower
and thunderstorm activity on Thursday, and given its placement
to our south, most of the day on Thursday is looking to be dry,
with only a low (20%) chance of a few showers. Thereafter, the
next impulse and wave of surface low pressure is forecast to
track eastward across the Mid-Mississippi Valley into Friday. As
this occurs, the focus for an area of rain activity may begin
to to shift back northward into southern sections of our area
(mainly areas south of I-80) Thursday night and on Friday.
Confidence on how far north this area of precipitation is able
to get into our area remains low at this time, owing to our
region likely remaining along the northern periphery of this
system.

This weekend into next week, ensemble forecast guidance
continues to be in good agreement with a larger scale weather
pattern change taking place across the central part of the
country. The main feature of this transitioning pattern is
expected to be the development of a subtropical ridge right
across the Mississippi Valley into the Great Lakes into early
next week. Locally, this is expected to result in a turn towards
hotter and more humid weather and an end to the below average
conditions. However, the extent of the hot and humid weather in
our region will ultimately be dependent upon convection trends
along the northern periphery of the upper ridge.

KJB

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 116 AM CDT Wed Jun 24 2026

Key Messages:

- Periods of showers are expected today, with probable scattered
  thunderstorms in the area this afternoon and evening.


An approaching mid/upper-level disturbance and associated low
pressure system will result in periodic shower and storm
chances today. Existing shower and thunderstorm activity across
southern Wisconsin, southern Minnesota, and northern Iowa early
this morning should gradually decay with time and eastward
extent, but the remnants of this activity may nevertheless
persist into our area this morning and bring about an initial
period of showers. RFD stands the greatest chance of seeing some
rain this morning, and there is also a lower-end chance (~15%)
of a few lightning strikes occurring near there this morning as
well.

Additional waves of showers and storms are likely to develop and
track southeastward through northern Illinois and northwest
Indiana this afternoon and evening. Pinpointing precisely where
and when the storms may occur remains a challenge -- partly
because the morning showers and associated cloud cover will
affect how quickly the necessary destabilization to support this
convection will be able to occur, and partly because of
uncertainties pertaining to where any initiating surface
boundaries may be present when sufficient destabilization is
eventually realized. As a result, have a relatively low
confidence 6-hour-long PROB30 group for TSRA present in all
five of our TAFs during the mid-afternoon and early evening,
when the potential for thunderstorms appears to be greatest at
the terminals. Refinements to this TSRA mention (and other
elements of the TAFs related to the shower and thunderstorm
activity) will likely be needed as observational trends become
apparent later today. Wherever storms do occur today, gusty wind
shifts and sub-VFR visibilities and ceilings may also occur.

Otherwise, VFR conditions with predominantly southwesterly winds
are expected through a majority of the TAF period.

Ogorek

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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